Method of enabling seamless cobalt gap-fill

ABSTRACT

Methods for depositing a metal layer in a feature definition of a semiconductor device are provided. In one implementation, a method for depositing a metal layer for forming a semiconductor device is provided. The method comprises performing a cyclic metal deposition process to deposit a metal layer on a substrate and annealing the metal layer disposed on the substrate. The cyclic metal deposition process comprises exposing the substrate to a deposition precursor gas mixture to deposit a portion of the metal layer on the substrate, exposing the portion of the metal layer to either a plasma treatment process or hydrogen annealing process and repeating the exposing the substrate to a deposition precursor gas mixture and exposing the portion of the metal layer to either a plasma treatment process or hydrogen annealing process until a predetermined thickness of the metal layer is achieved.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/482,601, filed Sep. 10, 2014, which claims benefit of U.S.provisional patent application Ser. No. 61/883,480, filed Sep. 27, 2013,both of which are herein incorporated by reference in their entirety.

BACKGROUND

Field

Implementations of the disclosure generally relate to the field ofsemiconductor manufacturing processes, more particularly, to methods fordepositing metal containing layers in features of a semiconductordevice.

Description of the Related Art

Integrated circuits may include more than one million micro-electronicfield effect transistors (e.g., complementary metal-oxide-semiconductor(CMOS) field effect transistors) that are formed on a substrate (e.g.,semiconductor wafer) and cooperate to perform various functions withinthe circuit. Reliably producing sub-half micron and smaller features isone of the key technologies for the next generation of very large scaleintegration (VLSI) and ultra large-scale integration (ULSI) ofsemiconductor devices. However, as the limits of integrated circuittechnology are pushed, the shrinking dimensions of interconnects in VLSIand ULSI technology have placed additional demands on processingcapabilities. Reliable formation of the gate pattern is important tointegrated circuits success and to the continued effort to increasecircuit density and quality of individual substrates and die.

As feature sizes have become smaller, the demand for higher aspectratios, defined as the ratio between the depth of the feature and thewidth of the feature, has steadily increased to 20:1 and even greater. Avariety of problems may occur when depositing metal layers into featuredefinitions with small geometries, such as geometries having aspectratios of about 20:1 or smaller. For example, a metal layer depositedusing a conventional PVD process often suffers from poor step coverage,overhang, and voids formed within the via or trench when the via has acritical dimension of less than 50 nm or has an aspect ratio greaterthan 10:1. Insufficient deposition on the bottom and sidewalls of thevias or trenches can also result in deposition discontinuity, therebyresulting in device shorting or poor interconnection formation.Furthermore, the metal layer may have poor adhesion over the underlyingmaterial layer, resulting in peeling of the metal layer from thesubstrate and the subsequent conductive metal layer.

With this increase in transistor density and subsequent decrease in thecross-sections of metal layers, meeting the contact resistancerequirements using existing low resistivity tungsten (W) integrationschemes has become quite challenging. The necessity of high-resistivityadhesion (e.g., B₂H₆ nucleation) and barrier layers (e.g., TiN) in thetungsten integration scheme results in increased contact resistancemaking it an unattractive option for technology nodes less than 22nanometers.

Therefore, there is a need for an improved method for forming a contactmetal layer in high aspect ratio features.

SUMMARY

Implementations of the disclosure generally relate to the field ofsemiconductor manufacturing processes, more particularly, to methods fordepositing a metal layer in structures of a semiconductor device. In oneimplementation, a method for depositing a metal layer for forming asemiconductor device is provided. The method comprises performing acyclic metal deposition process to deposit a metal layer in a featuredefinition formed in a substrate, comprising exposing the substrate to adeposition precursor gas mixture to deposit a portion of the metal layerin the feature definition, exposing the portion of the metal layer toeither a plasma treatment process or a hydrogen annealing process,repeating the exposing the substrate to a deposition precursor gasmixture and the exposing the portion of the metal layer to either aplasma treatment process or a hydrogen annealing process until apredetermined thickness of the metal layer is achieved and annealing themetal layer.

In another implementation, a method for depositing a metal layer forforming a semiconductor device is provided. The method comprisesperforming a barrier layer deposition process to deposit a barrier layerin a feature definition formed in a substrate, performing a wettinglayer deposition to deposit a wetting layer on the barrier layer,performing a cyclic metal deposition process to deposit a metal layer onthe wetting layer, and annealing the metal layer. The cyclic metaldeposition process comprises exposing the substrate to a depositionprecursor gas mixture to deposit a portion of the metal layer in thefeature definition, exposing the portion of the metal layer to either aplasma treatment process or a hydrogen annealing process, and repeatingthe exposing the substrate to a deposition precursor gas mixture andexposing the portion of the metal layer to either a plasma treatmentprocess or a hydrogen annealing process until a predetermined thicknessof the metal layer is achieved.

In yet another implementation, a method for depositing a metal layer forforming a semiconductor device is provided. The method comprisesperforming a barrier layer deposition process to deposit a barrier layerin a feature definition formed in a substrate, performing a wettinglayer deposition process to deposit a wetting layer on the barrierlayer, performing an annealing process on the wetting layer, performinga metal deposition process to deposit a metal layer on the wetting layerby exposing the wetting layer to a deposition precursor gas mixture todeposit a portion of the metal layer, exposing the portion of the metallayer to a either a plasma treatment process or a hydrogen annealingprocess, and annealing the metal layer.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description ofthe implementations, briefly summarized above, may be had by referenceto implementations, some of which are illustrated in the appendeddrawings. It is to be noted, however, that the appended drawingsillustrate only typical implementations of this disclosure and aretherefore not to be considered limiting of its scope, for the disclosuremay admit to other equally effective implementations.

FIG. 1 depicts a sectional view of one implementation of a metaldeposition processing chamber suitable for performing implementationsdescribed herein;

FIG. 2 depicts a schematic top-view diagram of an illustrativemulti-chamber processing system having the metal deposition processingchamber of FIG. 1 incorporated therein;

FIG. 3 depicts a flow diagram for forming a metal layer in asemiconductor device in accordance with certain implementationsdescribed herein;

FIGS. 4A-4E depict cross-sectional views of a semiconductor deviceduring the formation of a metal layer manufacture process in accordancewith one implementation of the present disclosure; and

FIG. 5 depicts a flow diagram for a cyclic deposition process forforming a metal layer in a semiconductor device in accordance withcertain implementations described herein;

FIG. 6 depicts a flow diagram for forming a metal layer in asemiconductor device in accordance with certain implementationsdescribed herein;

FIGS. 7A-7E depict cross-sectional views of a semiconductor deviceduring the formation of a metal layer manufacture process in accordancewith certain implementations described herein;

FIG. 8 depicts a flow diagram for forming a metal layer in asemiconductor device in accordance with certain implementationsdescribed herein;

FIG. 9 depicts a cross-sectional view of a substrate containing metallayers used as a conformal gate electrode and deposited according tocertain implementations described herein; and

FIG. 10 depicts a cross-sectional view of a CMOS structure having NMOSand PMOS aspects formed according to certain implementations describedherein.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneimplementation may be beneficially incorporated in other implementationswithout further recitation. It is to be noted, however, that theappended drawings illustrate only exemplary implementations of thisdisclosure and are therefore not to be considered limiting of its scope,for the disclosure may admit to other equally effective implementations.

DETAILED DESCRIPTION

The increase in transistor density combined with the shrinkingtechnology nodes (≤11 nm) of advanced CMOS transistors has resulted indecrease in the cross-section dimensions of conducting metal layersutilized during semiconductor manufacturing. Examples of such metalconducting layers include metal contact fill, metal gate fill andinterconnect fill. Very narrow cross-section dimensions (<20 nm) forthese application necessitates a metal fill technology without the needof thick (>2 nm) high resistivity barrier layers. Gap-fill methodsutilizing CVD cobalt processes provide a potential low contactresistance (Rc) one-material solution for gap-fill. The CVD cobalt filmsare required to have conformal step coverage and low roughness. Certainimplementations described herein demonstrate a process to fillconducting layer holes or trenches of a semiconductor device with noseam formation.

In some implementations, the purity of the cobalt film was found togovern cobalt seamless fill. The atomic % of carbon, nitrogen and oxygenimpurities in the CVD cobalt film may be controlled through processtemperature, process gases, cyclic plasma treatment (H₂, N₂, etc.) andpost-deposition anneal conditions (in Ar or H₂ or combination thereof).The re-flow characteristic of CVD cobalt film may be regulated bycontrolling atomic % of impurities through above-mentioned processvariables. The impurities may be in the form of carbon, oxygen,nitrogen, etc. In some implementations, 1% or lower carbon impuritylevel was preferable for enabling seamless cobalt gap-fill.

In some implementations, cyclic H₂ plasma treatment of CVD cobalt layerwas used to reduce roughness and carbon % of the deposited films. Thus,H* radical lifetime, especially inside the narrow (e.g., <15 nm CDand >5 aspect ratio) via and trench structures expected for transistortechnology node≤14 nm, was an important parameter to enable seamless andvoid-free cobalt gap-fill. In some implementations, increasing thefrequency of the plasma treatment during CVD cobalt deposition allowedfor void-free cobalt gap-fill. The life time of H* radical inside theCVD chamber may be improved by flowing an inert, stable gas (such ashelium, neon, argon, etc.) during plasma treatment step or by using aninductively coupled plasma source or microwave plasma source or e-beamplasma source. Alternatively, H₂ purge at pressures (15-60 Torr) can beutilized in place of H₂ plasma. This is especially useful if short H*radical lifetime does not allow H* radical to reach to the bottom ofhigh aspect ratio (e.g., for >10:1) features.

In some implementations, cobalt was deposited using dicobalthexacarbonyl tertbutyl acetylene (CCTBA) precursors in chemical vapordeposition (CVD) mode. However, alternate cobalt precursors can also beused to deposit cobalt film layers in either chemical vapor depositionor atomic layer deposition (ALD) mode. Some of the cobalt precursorsthat may be used include cobalt amidinate, cyclopentadienyl cobaltdicarbonyl, cobalt carbonyl, cobalt diazadienyl complexes, cobalttricarbonyl nitrosyl, cobalt acetylacetonate, cobalthexafluoroacetylacetonate, cobalt hydride complexes, cobalt (II)acetate, and cobalt (II) acetylacetonate. In addition, the annealingstep may be combined with CVD or ALD deposition by using processtemperatures in the range of 200-500° C. and in presence of process gassuch as Ar or H₂.

Instead of CVD and ALD deposition of cobalt, physical vapor deposition(PVD) may also be used for seamless gap-fill of cobalt. Similar to theprocess described above, a cyclic PVD cobalt deposition and annealingprocess can be used for seamless filling of the feature definition.Alternatively, high temperature (200-500° C.) PVD cobalt deposition inthe presence of a process gas such as Ar or H₂ may be used. Since PVD isa ‘line of sight’ deposition process, a wetting layer may be preferablefor PVD cobalt reflow. The wetting layer may be any of MO TiN, CVDcobalt, CVD Ru, ALD TaN. Alternatively, the PVD cobalt layer depositedat the bottom of the feature may be etched and re-sputtered on thesidewall of the feature definition to provide a continuous cobalt filmon the sidewall allowing for re-flow of PVD cobalt from the field to thebottom of the feature definition.

In some implementations, the re-flow of cobalt films may be enabledusing an integrated anneal (with no vacuum break) in the dual mode degaschamber. In some implementations, the re-flow of cobalt films may beachieved by annealing after vacuum break. In some implementations, ananneal temperature of 300-400° C. may be preferable for enablingseamless gap-fill. However, a range of temperature such as 200-500° C.may be used. In some implementations, annealing in an ambient of H₂improved cobalt seamless fill. Other ambient such as H₂ mixed with inertas well as pure inert (Ar or N₂) may be used for annealing. Other annealvariables include anneal time and anneal state (flow or static).

Potential applications of the implementations described herein includemetal-gate fill, interconnect fill and contact fill. Certainimplementations described herein enable use of cobalt as pMOSwork-function metal as well as metal gate fill material by allowing forlow-resistivity seamless cobalt fill. Incumbent metal gate fill material(tungsten) requires thick (>2 nm) TiN barrier and high resistivitytungsten-nucleation layer prior to tungsten deposition.

Certain implementations described herein may be utilized to fill viasand/or trenches of the interconnect structures with cobalt utilizing noor thin (≤1 nm) TiN barrier layer. Conventional copper fill integrationscheme requires thick (>2 nm) barrier layers (such as Ta and TaN) priorto copper fill.

Certain implementations described herein may be utilized to fill contactvias and trenches with cobalt utilizing a thin (1 nm) TiN barrier tostop cobalt diffusion in the semiconductor junction substrate.

Implementations of the present disclosure provide gap-fill utilizingmetallic CVD and PVD processes (e.g., cobalt CVD and PVD processes)resulting in a potential low contact resistance (Rc) one-materialsolution for metal filling of feature definitions. The metal layersdeposited according to implementations described herein may be used as awork function material, a metal gate fill, a metal contact fill, and aninterconnect fill. Exemplary feature definitions include featuredefinitions such as vias, trenches, lines, contact holes, or otherfeature definitions utilized in a semiconductor, solar, or otherelectronic devices, such as high aspect contact plugs. The CVD and PVDfilms deposited according to implementations described herein haveconformal step coverage and low surface roughness. Further, theimplementations demonstrated herein demonstrate a process for fillingfeature definitions of a semiconductor device with no seam formation.

In one implementation, a method for depositing a metal layer over asubstrate is provided which includes exposing the substrate to a cobaltprecursor gas and hydrogen gas to selectively form a portion of aseamless gap fill cobalt layer within a feature definition, and exposingthe cobalt layer to a plasma and a reagent, such as nitrogen, ammonia,hydrogen, an ammonia/nitrogen mixture, or combinations thereof during apost-treatment process.

As used herein, the term high-k dielectric material includes adielectric material having a dielectric constant greater than 10.Suitable high-k dielectric materials include a dielectric materialhaving a dielectric constant of 25 or greater. One class of high-kdielectric material that may be used includes one or more oxidematerials. Examples of suitable oxide materials include hafnium oxide,hafnium silicate, hafnium silicon oxynitride, aluminates thereof, orderivatives thereof or combinations thereof. Other oxide materialsinclude lanthanum oxide, lanthanum silicate, zirconium oxide, zirconiumsilicate, or combinations thereof. Each of the one or more oxidematerials may also be doped with a material selected from the group ofzirconium, lanthanum, cerium, titanium, or combinations thereof.

As used herein, the term “substrate” refers to a layer of material thatserves as a basis for subsequent processing operations and includes asurface to be disposed for forming a metal layer thereon. The substratemay be a material such as crystalline silicon (e.g., Si<100> orSi<1111>), silicon oxide, strained silicon, silicon germanium, doped orundoped polysilicon, doped or undoped silicon wafers, patterned ornon-patterned wafers silicon on insulator (SOI), carbon doped siliconoxides, silicon nitride, doped silicon, germanium, gallium arsenide,glass, or sapphire. The substrate may comprise dielectric materials suchas silicon dioxide (SiO₂), or a high-k dielectric material having adielectric constant greater than 4.0, such as SiON, SiN, hafnium oxide(HfO₂), hafnium silicate (HfSiO₂), hafnium silicon oxynitride (HfSiON),zirconium oxide (ZrO₂), zirconium silicate (ZrSiO₂), barium strontiumtitanate (BaSrTiO₃, or BST), lead zirconate titanate (Pb(ZrTi)O₃, orPZT), and the like. The substrate can also include one or morenonconductive materials, such as silicon, silicon oxide, doped silicon,germanium, gallium arsenide, glass, and sapphire. The substrate can alsoinclude dielectric materials such as silicon dioxide, organosilicates,and carbon doped silicon oxides. Further, the substrate can include anyother materials such as metal nitrides and metal alloys, depending onthe application.

As used herein, the term “work function” is a material property,measured in electron volts (eV), which represents the amount of energyneeded to remove an electron from a solid to a point outside the solidsurface or the energy needed to move an electron from the Fermi levelinto a vacuum. In practice, the work function value is the amount ofenergy needed to move the metal electron from the metal to the high-kmaterial. It is believed that the value is close to the ideal workfunction and may sometimes vary due to the structure of the metal thatis deposited on the dielectric material. For a metal, the work functionis a constant, and for a semiconductor material, the work function canbe modified by the addition of other materials, such as boron orphosphorus, generally considered dopant materials. A transistor'sthreshold voltage may be modified when using materials having differentdesired work functions in a metal gate electrode structure.

As used herein, the term “work function material” refers to a materialhaving work function material properties and used to form the desiredproperties, such as electrical properties, of a gate electrode in atransistor structure. The work function material may be disposed on oradjacent to a high-k dielectric material to provide the most effect ofthe work function material's properties on the metal gate electrodestructure of a transistor. The work function required will depend on thehigh-k material and the doping type and amount of the source, drain, andgate. Thus, the composition of the work function metal may need to bevaried to achieve the desired amount. The work function of N-metalplanar gate structures should typically be equal to or less than 4.3 eV,whereas the work function for non-planar gate structures such as FinFETgate structures, where higher doping is acceptable, may be equal to orless than 4.4 eV. The work function for a given circuit design dependson the amount of doping allowed.

The work function material may be a metal, metal carbide, metalsilicide, metal carbide silicide, metal carbide nitride, or metal boridematerial described herein and deposited by the processes describedherein. Additionally, the metal, metal carbide, metal silicide, metalcarbide silicide, metal carbide nitride, or metal boride materials maycontain other conductive materials, such as aluminum. Suitable workfunction materials include a material selected from the group oftantalum, hafnium, titanium, lanthanum, tantalum carbide, hafniumcarbide, titanium carbide, lanthanum carbide, hafnium silicides,tantalum silicides, titanium silicides, lanthanum silicides, tantalumcarbide silicide, hafnium carbide silicide, titanium carbide silicide,lanthanum carbide silicide, hafnium aluminide carbide, tantalumaluminide carbide, lanthanum aluminide carbide, tantalum carbidenitride, tantalum aluminide nitride, lanthanum boride, hafnium boride,or combinations thereof. Additionally, the work function material may bedeposited, for example, to a thickness of about 20 Å or more, such asfrom about 20 Å to about 80 Å, for example, about 30 Å thick.

In one or more implementations, the substrate can form a gate structureincluding a gate dielectric layer and a gate electrode layer tofacilitate connecting with an interconnect feature definition, such as aplug, via, contact, line, and wire, subsequently formed thereon. Thesubstrate may have various dimensions, such as 200 mm, 300 mm, or 450 mmdiameter wafers or other dimensions, as well as rectangular or squarepanels. Unless otherwise noted, implementations and examples describedherein may be conducted on substrates with a 200 mm diameter, a 300 mmdiameter, or a 450 mm diameter, particularly a 300 mm diameter.

As used herein, the term “contact structure” refers to a layer ofmaterial that includes a contact metal layer that can form part of agate electrode. In one or more implementations, the contact metal layercan be nickel layer, cobalt layer, titanium layer or any combinationsthereof.

Moreover, the substrate is not limited to any particular size or shape.The substrate can be a round wafer having a 200 mm diameter, a 300 mmdiameter or other diameters, such as 450 mm, among others. The substratecan also be any polygonal, square, rectangular, curved or otherwisenon-circular workpiece, such as a polygonal glass substrate used in thefabrication of flat panel displays.

Implementations described herein provide methods for depositing/forminga metal layer within a feature definition to form a metal structure. Thedeposition process may efficiently improve deposited film step coverage,conformality, and continuity and uniformity across the substrate,thereby improving the overall film properties formed across thesubstrate.

FIG. 1 illustrates a processing chamber 150 that may be used to formmetal materials by vapor deposition processes as described herein. Themetal materials may contain metallic cobalt, metallic nickel,derivatives thereof, or combinations thereof. The processing chamber 150may be used to perform CVD, plasma enhanced-CVD (PE-CVD), pulsed-CVD,ALD, PE-ALD, derivatives thereof, or combinations thereof. Theprocessing chamber 150 may be used to anneal previously deposited metallayers. Thus, both the deposition processes and the subsequent annealingmay be performed in-situ in the same processing chamber. Water channels,such as a convolute liquid channel 162, may be used to regulate thetemperature of a lid assembly 100 during the vapor deposition processfor depositing a cobalt-containing material. In one implementation, thelid assembly 100 may be heated or maintained at a temperature within arange from about 100° C. to about 300° C., preferably, from about 125°C. to about 225° C., and more preferably, from about 150° C. to about200° C. The temperature may be maintained during the vapor depositionprocess of a cobalt-containing material and/or nickel containingmaterial.

A showerhead 156 has a relatively short upwardly extending rim 158coupled with a gas box plate 160. Both the showerhead 156 and the gasbox plate 160 may be formed from or contain a metal, such as aluminum,stainless steel, or alloys thereof. The convolute liquid channel 162 isformed in the top of the gas box plate 160 and covered and sealed by awater cooling cover plate 134. Water is generally flown through theconvolute liquid channel 162. However, alcohols, glycol ethers, andother organic solvents may be used solely or mixed with water totransfer heat away from or to the lid assembly 100. The convolute liquidchannel 162 is formed in a serpentine though generally circumferentialpath having bends (e.g., three sharp U-turns or U-shaped bends) as thepath progresses from the inside to the outside until the path returns tothe inside in a radial channel (not shown). The convolute liquid channel162 is narrow enough to ensure that the flow of water becomes turbulent,thus aiding the flow of heat from the flange of the gas box plate 160 tothe water in the convolute liquid channel 162. A liquid temperatureregulating system (not shown) may be attached to the convolute liquidchannel 162 and used to transfer heat away from or to lid assembly 100.In one example, the lid assembly 100 is configured to be heated ormaintained at a temperature of about 150° C. and is in fluidcommunication with a source of a cobalt precursor, such as dicobalthexacarbonyl butylacetylene “CCTBA,” and a source of a hydrogenprecursor, such as H₂.

The extending rim 158 of the showerhead 156 is attached to the bottomrim 171 of the gas box plate 160. Both rims 158 and 171 are maximallysized between encompassing a lid isolator 175 and an encompassed lowercavity 130 of the showerhead 156. A screw fastening between theshowerhead 156 and the gas box plate 160 ensures good thermal contactover the maximally sized contact area. The thermal flow area extendsfrom the outside at the lid isolator 175 (except for a gap between thelid isolator 175 and either the showerhead 156 or the gas box plate 160)to the inside at a lower cavity 130. The structure of the convoluteliquid channel 162 provides efficient thermal transfer between the waterand the gas box plate 160. The mechanical interface between the flangeof gas box plate 160 and showerhead 156 ensures efficient thermaltransfer between the gas box plate 160 and the showerhead 156.Accordingly, cooling of the showerhead 156 is greatly enhanced.

The processing chamber 150 further contains a heater pedestal 152connected to a pedestal stem 154 that may be vertically moved within theprocessing chamber 150. The heater portion of the heater pedestal 152may be formed of a ceramic material. In its upper deposition position,the heater pedestal 152 holds a substrate 402 in close opposition to alower surface 107 of the showerhead 156. A processing region 126 isdefined between the heater pedestal 152 and the lower surface 107 of theshowerhead 156. The showerhead 156 has a plurality of apertures or holes109 communicating between the lower cavity 130 and the processing region126 to allow for the passage of processing gas. The processing gas issupplied through the gas port 132 formed at the center of thewater-cooled gas box plate 160 which is made of aluminum. The upper sideof the gas box plate 160 is covered by a water-cooling cover plate 134surrounding the upper portion of the gas box plate 160 that includes agas port 132. The gas port 132 supplies the processing gases to an uppercavity 138, which is separated from the lower cavity 130 by a blockerplate 140. The blocker plate 140 has a large number of holes 109disposed therethrough. In one implementation, the cavities 130 and 138,showerhead 156, and blocker plate 140 evenly distribute the processinggas over the upper face of the substrate 402.

The substrate 402 may be supported on the heater pedestal 152, which isillustrated in a raised, deposition position. In a lowered, loadingposition, a lifting ring 116 is attached to a lift tube 117, which liftsfour lift pins 118. The lift pins 118 fit to slide into the heaterpedestal 152 so that the lift pins 118 can receive the substrate 402loaded into the chamber through a loadlock port 119 in a chamber body120. In one implementation, the heater pedestal 152 may contain anoptional confinement ring 110, such as during plasma-enhanced vapordeposition processes.

A side purge gas source 123 may be coupled to the processing chamber 150and configured to supply purge gas to an edge portion 151 of thesubstrate 402 as needed. In one implementation, the gases may besupplied from the side purge gas source 123 to the substrate 402 edgeportion 151. The gasses may be a hydrogen gas, argon gas, nitrogen gas,helium gas, combinations thereof, or the like. Furthermore, a bottompurge gas source 125 may also be coupled to the processing chamber 150to supply the purge gas from the bottom of the processing chamber 150 tothe substrate 402 surface. Similarly, the purge gas supplied from thebottom purge gas source 125 may include a hydrogen gas, argon gas,nitrogen gas, helium gas, combinations thereof, or the like.

A lid isolator 175 is interposed between showerhead 156 and a lid rim166, which can be lifted off the chamber body 120 to open the processingchamber 150 for maintenance access. The vacuum within the processingchamber 150 is maintained by a vacuum pump 170 connected to a pumpplenum 172 within the processing chamber 150, which connects to anannular pumping channel 174.

An annular chamber liner 179 made of quartz is disposed in theprocessing chamber 150 which defines a side of the annular pumpingchannel 174 but also partially defines a further choke aperture 181disposed between the processing region 126 and the annular pumpingchannel 174. The annular chamber liner 179 also supports the confinementring 110 in the lowered position of the heater pedestal 152. The chamberliner 179 also surrounds a circumference at the back of the heaterpedestal 152. The chamber liner 179 rests on a narrow ledge in chamberbody 120, but there is little other contact, to minimize thermaltransport. Below the chamber liner 179 is located a lower chamber shield121, made of opaque quartz. The lower chamber shield 121 may be az-shaped chamber shield. The lower chamber shield 121 rests on thebottom of chamber body 120 on an annular boss 177 formed on the bottomof the lower chamber shield 121. The quartz prevents radiative couplingbetween the bottom of the heater pedestal 152 and the chamber body 120.The annular boss 177 minimizes conductive heat transfer to the chamberbody 120. In an alternative implementation, the lower chamber shield 121includes an inwardly extending bottom lip joined to a conically shapedupper portion conforming to the inner wall of chamber body 120. Whilethis alternative design is operationally satisfactory, the sloping shapeis much more expensive to fabricate in quartz.

In one implementation, a remote plasma source 141 may be coupled to theprocessing chamber 150 through a gas port 132 to supply reactive plasmafrom the remote plasma source 141 through the plurality of holes 109 inthe showerhead 156 to the processing chamber 150 to the substrate 402surface. It is noted that the remote plasma source 141 may be coupled tothe processing chamber 150 in any suitable position to supply a reactiveremote plasma source to the substrate 402 surface as needed. Suitablegases that may be supplied to the remote plasma source 141 to bedissociated and further delivered to the substrate 402 surface includehydrogen, argon, helium, nitrogen, ammonia, combinations thereof and thelike.

In FIG. 1, a control unit 180 may be coupled to the processing chamber150 to control processing conditions. The control unit 180 comprises acentral processing unit (CPU) 182, support circuitry 184, and memory 186containing associated control software 183. The control unit 180 may beone of any form of a general purpose computer processor that can be usedin an industrial setting for controlling various chambers andsub-processors. The CPU 182 may use any suitable memory 186, such asrandom access memory, read only memory, floppy disk drive, compact discdrive, hard disk, or any other form of digital storage, local or remote.Various support circuits may be coupled to the CPU 182 for supportingthe processing chamber 150. The control unit 180 may be coupled toanother controller that is located adjacent individual chambercomponents. Bi-directional communications between the control unit 180and various other components of the processing chamber 150 are handledthrough numerous signal cables collectively referred to as signal buses,some of which are illustrated in FIG. 1.

FIG. 2 is a schematic top view diagram of an illustrative multi-chamberprocessing system 200 that can be adapted to perform a metal layerdeposition process as disclosed herein having a processing chamber 150as described above in reference to FIG. 1, integrated therewith. Thesystem 200 can include one or more load lock chambers 202 and 204 fortransferring substrate 402 into and out of the system 200. Generally,the system 200 is maintained under vacuum and the load lock chambers 202and 204 can be “pumped down” to introduce substrate 402 introduced intothe system 200. A first robot 210 can transfer the substrate 402 betweenthe load lock chambers 202 and 204, and a first set of one or moresubstrate processing chambers 212, 214, 216, and 150. Each processingchamber 212, 214, 216, and 150 is configured to be at least one of asubstrate deposition process, such as cyclical layer deposition (CLD),atomic layer deposition (ALD), chemical vapor deposition (CVD), physicalvapor deposition (PVD), etch, degas, pre-cleaning orientation, anneal,and other substrate processes. Furthermore, one of the processingchambers 212, 214, 216, and 150 may also be configured to perform apre-clean process prior to performing a deposition process or a thermalannealing process on the substrate 402. The position of the processingchamber 150 utilized to perform a thermal annealing process relative tothe other chambers 212, 214, 216 is for illustration, and the positionof the processing chamber 150 may be optionally be switched with any oneof the processing chambers 212, 214, 216 if desired.

The first robot 210 can also transfer substrate 402 to/from one or moretransfer chambers 222 and 224. The transfer chambers 222 and 224 can beused to maintain ultrahigh vacuum conditions while allowing substrate402 to be transferred within the system 200. A second robot 230 cantransfer the substrate 402 between the transfer chambers 222 and 224 anda second set of one or more processing chambers 232, 234, 236 and 238.Similar to the processing chambers 212, 214, 216, and 150, theprocessing chambers 232, 234, 236, and 238 can be outfitted to perform avariety of substrate processing operations including the dry etchprocesses described herein in addition to cyclical layer deposition(CLD), atomic layer deposition (ALD), chemical vapor deposition (CVD),physical vapor deposition (PVD), etch, pre-clean, degas, andorientation, for example. Any of the substrate processing chambers 212,214, 216, 232, 234, 236, and 238 can be removed from the system 200 ifnot necessary for a particular process to be performed by the system200. After the preclean, deposition and/or a thermal annealing processis performed in the processing chamber 150, the substrate may further betransferred to any of the processing chambers 212, 214, 216, 232, 234,236, and 238 of the system 200 to perform other process as needed.

FIG. 3 illustrates a flow diagram of one implementation of a processingsequence 300 used to deposit a metal layer within a feature definitionof a semiconductor device structure on a substrate. The sequencedescribed in FIG. 3 corresponds to the fabrication stages depicted inFIGS. 4A-4E, which are discussed below. FIGS. 4A-4E illustrate schematiccross-sectional views of a substrate 402 having a device structure 408formed thereon during different stages of fabricating a metal layer 420within a feature definition of the device structure 408 illustrated bythe processing sequence 300. The sequence of FIG. 3 is generallyprovided with reference to a CVD, ALD, or PVD deposited cobalt metallayer.

Possible integration schemes include but are not limited to: (a) PVDTi+ALD TiN; (b) PVD Ti+CVD Co; (c) CVD Co; and (d) CVD Co+PVD Co. PVD Tiprovides good electrical contact with underlying silicide at source ordrain. ALD TiN improves adhesion of the cobalt film, if needed to helpre-flow of the cobalt film. CVD Co: cobalt fill using CVD films or CVDfollowed by re-flow.

The processing sequence 300 starts at block 310 by providing a substratehaving a feature definition formed within, such as the substrate 402having feature definitions 406 a, 406 b (collectively 406) formedtherein as depicted in FIG. 4A, into the processing chamber, such as thesubstrate 402 disposed in the processing chamber 150 depicted in FIG. 1,or other suitable processing chamber. The substrate 402 shown in FIG. 4Aincludes a semiconductor device structure 408 (e.g., such as a contactstructure, a gate structure or an interconnect structure) formed on thesubstrate 402. It is noted that this particular device structure 408 maybe used in three-dimensional (3-D) flash memory applications, DRAMapplications, or other suitable applications with high aspect ratio orother odd geometries.

A layer 404 is formed on the substrate 402 having feature definitions406 a, 406 b formed therein with high aspect ratios, such as aspectratios greater than 10:1, for example about greater than 20:1. Thefeature definitions 406 a, 406 b are formed in the device structure 408and have sidewalls 412 and a bottom 414 which form an open channel toexpose the underlying layer 404. The layer 404 may include any suitablelayers such as a single silicon layer, high-k dielectric layer, low-kdielectric layer or a multiple layer film stack having at least one ofthe aforementioned layers formed therein. In the implementation whereinthe layer 404 is in the form of a single layer, the layer 404 may be asilicon oxide layer, an oxide layer, a silicon nitride layer, a nitridelayer, a silicon oxynitride layer, a titanium nitride layer, apolysilicon layer, a microcrystalline silicon layer, a monocrystallinesilicon, a doped polysilicon layer, a doped microcrystalline siliconlayer, or a doped monocrystalline silicon.

In another example, where layer 404 is a silicon containing layer, thelayer 404 may be a film stack including a composite oxide and nitridelayer, at least one or more oxide layers sandwiching a nitride layer,and combinations thereof. Suitable dopants doped in the siliconcontaining layer 404 may include p-type dopants and n-type dopants, suchas boron (B) containing dopants or phosphine (P) containing dopants. Inone implementation wherein the layer 404 is in form of a multiple filmstack having at least one silicon containing layer, the siliconcontaining layer 404 may include repeating pairs of layers including asilicon containing layer and a dielectric layer. In one implementation,the layer 404 may include a polysilicon layer and/or other metalmaterials and/or a dielectric layer disposed therein. Suitable examplesof the dielectric layer may be selected from a group consisting of anoxide layer, silicon oxide layer, a silicon nitride layer, a nitridelayer, titanium nitride layer, a composite of oxide and nitride layer,at least one or more oxide layers sandwiching a nitride layer, andcombinations thereof, among others.

Prior to transferring the substrate 402 into the metal depositionprocessing chamber described at block 310, a pre-cleaning process isoptionally performed to treat the substrate surface 411, sidewalls 412and bottoms 414 of the feature definitions 406 a, 406 b to remove nativeoxides or other sources of contaminants. Removal of native oxides orother sources of contaminants from the substrate 402 may provide a lowcontact resistance surface to form a good contact surface for forming ametal layer.

The pre-cleaning process performed includes supplying a pre-cleaning gasmixture into a pre-cleaning chamber. The pre-cleaning chamber may be aPreclean PCII, PCXT or SICONI™ chambers, which are available fromApplied Materials, Inc., Santa Clara, Calif. The pre-cleaning chambermay be incorporated in the illustrative multi-chamber processing system200 and may be configured to be one of the processing chambers 212, 214,216, 232, 234, 236, 238 of the system 200 as needed. It is noted thatother pre-cleaning chambers available from other manufactures may alsobe utilized to practice the implementations described herein.

The pre-cleaning process is performed by supplying a cleaning gasmixture into the pre-cleaning processing chamber incorporated in thesystem 200 to form a plasma from the pre-cleaning gas mixture forremoving the native oxide. In one implementation, the pre-cleaning gasmixture used to remove native oxides is a mixture of ammonia (NH₃) andnitrogen trifluoride (NF₃) gases. The amount of each gas introduced intothe processing chamber may be varied and adjusted to accommodate, forexample, the thickness of the native oxide layer to be removed, thegeometry of the substrate being cleaned, the volume capacity of theplasma, the volume capacity of the chamber body, as well as thecapabilities of the vacuum system coupled to the chamber body.

In one or more implementations, the gases added to provide apre-cleaning gas mixture having at least a 1:1 molar ratio of ammonia(NH₃) to nitrogen trifluoride (NF₃). In one or more implementations, themolar ratio of the pre-cleaning gas mixture is at least about 3:1(ammonia to nitrogen trifluoride). The gases are introduced at a molarratio of from about 5:1 (ammonia to nitrogen trifluoride) to about 30:1.In yet another implementation, the molar ratio of the gas mixture isfrom about 5:1 (ammonia to nitrogen trifluoride) to about 10:1. Themolar ratio of the pre-cleaning gas mixture can also fall between about10:1 (ammonia to nitrogen trifluoride) and about 20:1.

A purge gas or carrier gas can also be added to the pre-cleaning gasmixture. Any suitable purge/carrier gas can be used, such as argon,helium, hydrogen, nitrogen, or mixtures thereof. The overallpre-cleaning gas mixture is from about 0.05% to about 20% by volume ofammonia and nitrogen trifluoride. The remainder of the pre-cleaning gasmixture may be the purge/carrier gas.

The operating pressure within the pre-clean chamber can be varied. Thepressure may be maintained between about 1 Torr and about 10 Torr. A RFsource power may be applied to maintain a plasma in the cleaning gasmixture. For example, a power of about 15 Watts to about 100 Watts maybe applied to maintain a plasma inside the pre-cleaning processingchamber. The frequency at which the power is applied is about 350 kHz.The frequency can range from about 50 kHz to about 350 kHz. The plasmaenergy dissociates the ammonia and nitrogen trifluoride gases intoreactive species, e.g., fluorine radicals and/or hydrogen radicals thatcombine to form a highly reactive ammonia fluoride (NH₄F) compoundand/or ammonium hydrogen fluoride (NH₄F.HF) in the gas phase. Thesemolecules are then delivered from the plasma location to the substratesurface to be cleaned. A purge/carrier gas can be used to facilitate thedelivery of the reactive species to the substrate. In oneimplementation, a titanium layer may be deposited after the pre-cleaningprocess. The titanium layer operates to gather any remaining oxygen atthe interface of the via and the underlying substrate which provides forimproved electrical contact with the underlying substrate.

At block 320, prior to deposition of a metal layer on the substrate 402,but after the substrate 402 is provided in the metal depositionprocessing chamber 150 at block 310, a pretreatment process may beperformed to pre-treat the substrate surface 411, thus, forming atreated surface region 410 on the substrate surface 411, sidewalls 412and bottoms 414 of the feature definitions 406 a, 406 b in the layer404, as shown in FIG. 4B. It should be noted that although two featuredefinitions 406 a, 406 b are shown, the substrate 402 may have anynumber of feature definitions 406. In certain implementations, thesubstrate surface 411 may have some weak or residual dangling bondingstructures of Si—F, N—F, H—F, and Si—N on the substrate surface leftfrom the optional pre-cleaning process previously performed on thesubstrate 402. The dangling bonds may undesirably and adversely obstructabsorption or adherence of metallic atoms deposited on the substratesurface in the subsequent metal deposition process. Thus, thepretreatment process at block 320 may be performed to efficiently alterthe surface bonding structure of the substrate surface 411 of thesilicon containing layer 404, thereby providing a surface having a goodabsorption ability to promote adherence of metallic atoms provided fromthe subsequent metal deposition process. It is believed that thepretreatment process may efficiently convert or remove the bondingstructure of Si—F, H—F, N—F, and Si—N, into the bonding of Si—H orSi—Si, which may assist in the adherence of the metallic atoms to form alayer thereon.

In one implementation, a pre-treatment gas mixture may be supplied intothe metal deposition processing chamber 150 to alter the surfaceproperties of the substrate 402 prior to the metal deposition process.In one implementation, the pre-treatment gas mixture may include atleast a hydrogen containing gas, such as H₂, H₂O, H₂O₂, or the like. Aninert gas, such as Ar, He, Kr, and the like, may also be supplied intothe pre-treatment gas mixture. Additionally, a nitrogen containing gas,such as N₂, NH₃, N₂O, NO₂, and the like, may also be supplied into thepre-treatment gas mixture. In an exemplary implementation, thepre-treatment gas mixture supplied to pre-treat the substrate surface411 includes a hydrogen containing gas, such as a H₂ gas, and an inertgas, such as Ar gas. In another exemplary implementation, thepre-treatment gas mixture supplied to pre-treat the substrate surface411 includes a hydrogen containing gas, such as a H₂ gas, an inert gas,such as Ar gas, and a nitrogen containing gas, such as a NH₃ gas.

The pre-treatment gas mixture may be supplied from a remote plasmasource, such as the remote plasma source 141 coupled to the metaldeposition processing chamber 150, to supply the pre-treatment gasmixture plasma remotely from the processing chamber 150 to the substratesurface 411. Alternatively, the pre-treatment gas mixture may besupplied from any other suitable sources installed in the processingchamber 150 to the substrate surface 411.

During the pretreatment process at block 320, several process parametersmay be regulated to control the pretreatment process. In one exemplaryimplementation, a process pressure in the metal deposition processingchamber 150 is regulated between about 50 mTorr to about 5000 mTorr,such as between about 500 mTorr and about 1000 mTorr, for example, atabout 700 mTorr. An RF source power may be applied to maintain a plasmain the pretreatment gas mixture. For example, a power of about 1000Watts to about 6000 Watts may be applied to maintain a plasma inside theprocessing chamber 150. The hydrogen containing gas supplied in thepretreatment gas mixture may be flowed into the processing chamber 150at a rate between about 400 sccm to about 4000 sccm and the inert gassupplied in the pretreatment gas mixture may be flowed at a rate betweenabout 200 sccm and about 2000 sccm. The nitrogen containing gas suppliedin the pretreatment gas mixture may be flowed at a rate between about100 sccm and about 3000 sccm. A temperature of the substrate 402 ismaintained between about 125 degrees Celsius to about 250 degreesCelsius. In one implementation, the substrate 402 is subjected to thepretreatment process for between about 10 seconds to about 2 minutes,depending on the operating temperature, pressure, and flow rate of thegas. For example, the substrate 402 can be exposed for about 30 secondsto about 60 seconds. In an exemplary implementation, the substrate isexposed for about 40 seconds or less.

Optionally, at block 330 a barrier layer deposition process may beperformed to deposit a barrier layer 416 in the feature definitions 406a, 406 b as shown in FIG. 4C. The barrier layer 416 generally preventsdiffusion of the metal layer to the junction material on the substrate,typically a silicon or silicon germanium compound. The barrier layergenerally contains a metal or a metal nitride material, such as titanium(Ti), titanium nitride (TiN), alloys thereof, or combinations thereof.The barrier layer 416 may also comprise plasma nitrided (N₂ or NH₃) Tiand PVD Cobalt. If the barrier layer 416 comprises a nitrided Ti layer,only the top few angstroms of titanium are converted to a TiN compound.It has been found that both oxidized and non-oxidized Ti and TiN barrierlayers provide for improved diffusion resistance. The barrier layer 416may have a thickness within a range from about 2 Å to about 100 Å, morenarrowly within a range from about 3 Å to about 80 Å, more narrowlywithin a range from about 4 Å to about 50 Å, more narrowly within arange from about 5 Å to about 25 Å, more narrowly within a range fromabout 5 Å to about 20 Å, more narrowly within a range from about 5 Å toabout 15 Å, and more narrowly within a range from about 5 Å to about 10Å. The barrier layer is generally deposited by atomic layer deposition(ALD), plasma-enhanced ALD (PE-ALD), chemical vapor deposition (CVD), orphysical vapor deposition (PVD) processes.

The barrier layer 416 is similar to a wetting layer, which is describedin detail below. The barrier layer 416, as described above, generallyprevents diffusion of the metal layer to the junction material on thesubstrate. A wetting layer generally enhances the adherence of the metallayer, Cobalt in some implementations, which reduces the formation ofundesirable voids in the feature definitions during annealing processesperformed on the metal layer.

At block 340, after the pre-treatment process of block 320 is performedon the substrate surface to form the treated surface region 410 ordeposition of the barrier layer 416 in block 330, a CVD or PVD metaldeposition process may be performed in the processing chamber 150 todeposit a metal layer 420, as shown in FIG. 4D. The metal layer 420 maybe deposited using the cyclic deposition process described in FIG. 5.The metal layer 420 fills the feature definitions 406 a, 406 b. Suitableexamples of the metal layer 420 include titanium (Ti), cobalt (Co),nickel (Ni), alloys thereof, or any combination thereof. In oneparticular implementation described therein, the metal layer 420deposited on the substrate 402 is a cobalt (Co) layer.

The metal layer 420 may be deposited using a multi-step depositionprocess comprising multiple cycles of performing a cyclic metaldeposition process to deposit the metal layer 420 followed by annealingthe metal layer 420. In certain implementations, the thickness of themetal layer 420 should be less than 50% of the feature definitiondiameter (critical dimension) of the smallest feature definition to befilled. For example, the cyclic metal deposition process is performed topartially fill a feature definition to less than half of the featuredefinition diameter followed by an anneal process. The cyclic depositionprocess followed by an anneal would then be repeated to deposit untilthe metal layer 420 achieved a predetermined thickness. In analternative implementation, the metal layer 420 may be deposited tocompletely fill the feature definition in a single, non-cyclicdeposition process. In this implementation, the metal layer 420 is thenannealed. The non-cyclic metal layer deposition process and subsequentanneal processes increase throughput because they require less time tocomplete.

FIG. 5 depicts a flow diagram for a cyclic deposition process as shownin block 340 for forming a metal layer, such as metal layer 420, in asemiconductor device in accordance with one implementation of thepresent disclosure. In one implementation, the process includes exposinga substrate to a deposition gas to form a portion of a metal layer(block 510), optionally purging the deposition chamber (block 520),exposing the substrate to either a plasma treatment process or anannealing process (block 530), optionally purging the deposition chamber(block 540), and determining if a predetermined thickness of the metallayer has been achieved (block 550). In one implementation, the cycle ofblocks 510-550 may be repeated if the cobalt metal layer has not beenformed having the predetermined thickness. Alternately, the process maybe stopped once the metal layer has been formed having the predeterminedthickness.

During the metal deposition process, the metal layer 420 may be formedor deposited by introducing a deposition precursor gas mixture includinga cobalt precursor or a nickel precursor simultaneously with,sequentially with, or alternatively without a reducing gas mixture(reagent), such as a hydrogen gas (H₂) or a NH₃ gas, into the metaldeposition processing chamber 150 during a thermal CVD process, apulsed-CVD process, a PE-CVD process, a pulsed PE-CVD process, or athermal ALD process. Additionally, the deposition precursor gas mixturemay also include a purge gas mixture supplied concurrently into theprocessing chamber for processing. In another implementation, the metallayer 420 may be formed or deposited by sequentially repetitivelyintroducing a pulse of the deposition precursor gas mixture, such as acobalt precursor, and a pulse of a reducing gas mixture, such as ahydrogen gas (H₂) or a NH₃ gas, into the metal deposition processingchamber 150 during a thermal ALD process or a pulsed PE-CVD process. Inanother implementation, the metal layer 420 may be formed or depositedby continuously flowing the reducing gas mixture, such as a hydrogen gas(H₂) or a NH₃ gas, while repetitively introducing a pulse of thedeposition precursor gas mixture, such as a cobalt precursor, and apulse of a reducing gas mixture into the metal deposition processingchamber 150 during a thermal ALD process or a pulsed PE-CVD process. Inanother implementation, the metal layer 420 may be formed or depositedby continuously flowing the reducing gas mixture, such as a hydrogen gas(H₂) or a NH₃ gas, and the deposition precursor gas mixture, such as acobalt precursor, under plasma conditions during a PE-CVD process. Inanother implementation, the metal layer 420 may be formed or depositedby continuously flowing the reducing gas mixture, such as a hydrogen gas(H₂) or a NH₃ gas under plasma conditions and periodically pulsing thedeposition precursor gas mixture, such as a cobalt precursor during aPE-CVD process.

Suitable cobalt precursors for forming cobalt-containing materials(e.g., metallic cobalt or cobalt alloys) by CVD or ALD processesdescribed herein include cobalt carbonyl complexes, cobalt amidinatescompounds, cobaltocene compounds, cobalt dienyl complexes, cobaltnitrosyl complexes, derivatives thereof, complexes thereof, plasmathereof, or combinations thereof. In some implementations, cobaltmaterials may be deposited by CVD and ALD processes further described incommonly assigned U.S. Pat. No. 7,264,846 and U.S. Ser. No. 10/443,648,filed May 22, 2003, and published as US 2005-0220998.

Suitable cobalt precursors may include, but not limited to, cobaltcarbonyl complexes, cobalt amidinates compounds, cobaltocene compounds,cobalt dienyl complexes, cobalt nitrosyl complexes, cobalt diazadienylcomplexes, cobalt hydride complexes, derivatives thereof, complexesthereof, plasmas thereof, or combinations thereof. In oneimplementation, examples of the cobalt precursors that may be usedherein include dicobalt hexacarbonyl butylacetylene (CCTBA,(CO)₆Co₂(HC≡C^(t)Bu)), dicobalt hexacarbonyl methylbutylacetylene((CO)₆Co₂(MeC≡C^(t)Bu)), dicobalt hexacarbonyl phenylacetylene((CO)₆Co₂(HC≡CPh)), hexacarbonyl methylphenylacetylene((CO)₆Co₂(MeC≡CPh)), dicobalt hexacarbonyl methylacetylene((CO)₆Co₂(HC≡CMe)), dicobalt hexacarbonyl dimethylacetylene((CO)₆Co₂(MeC≡CMe)), cobalt amidinate (C₂₀H₄₂CoN), cobalthexafluoroacetylacetone (Co(C₅HF₆O₂)₂·xH₂O), cobalt acetylacetonate((CH₃COC═COCH₃)₃Co), cobalt (II) acetlyacteonate ((CH₃COC═COCH₃)₂Co),cobalt acetate ((CH₃COO)₂Co), derivatives thereof, complexes thereof,plasmas thereof, or combinations thereof. Other exemplary cobaltcarbonyl complexes include cyclopentadienyl cobalt bis(carbonyl)(CpCo(CO)₂), tricarbonyl allyl cobalt ((CO)₃Co(CH₂CH═CH₂)), cobalttricarbonyl nitrosyl (Co(CO)₃NO), derivatives thereof, complexesthereof, plasmas thereof, or combinations thereof. In one particularexample of the cobalt precursors used herein is dicobalt hexacarbonylbutylacetylene (CCTBA, (CO)₆Co₂(HC≡C^(t)Bu)). It is noted that thedicobalt hexacarbonyl butylacetylene (CCTBA, (CO)₆Co₂(HC≡C^(t)Bu))precursor may be supplied into the metal deposition processing chamber150 with a carrier gas, such as an Ar gas.

Examples of the alternative reagents (i.e., reducing agents used withcobalt precursors for forming the cobalt materials during the depositionprocess as described herein may include hydrogen (e.g., H₂ or atomic-H),nitrogen (e.g., N₂ or atomic-N), ammonia (NH₃), hydrazine (N₂H₄), ahydrogen and ammonia mixture (H₂/NH₃), borane (BH₃), diborane (B₂H₆),triethylborane (Et₃B), silane (SiH₄), disilane (Si₂H₆), trisilane(Si₃H₈), tetrasilane (Si₄H₁₀), methylsilane (SiCH₆), dimethylsilane(SiC₂H₈), phosphine (PH₃), derivatives thereof, plasmas thereof, orcombinations thereof. In one particular example, the reagent or reducingagent used herein is ammonia (NH₃).

During the cyclic deposition process at block 340, in between each pulseof the deposition precursor gas mixture and the plasma pretreatmentprocess, a purge gas mixture may be supplied from a side/edge and/or abottom of the processing chamber 150 in between each or selecteddeposition precursor pulses to the edge portion 151 of the substrate402. The purge gas mixture may be supplied from the side and/or bottompurge gas source 123 and 125 disposed in the processing chamber 150 tosupply the purge gas mixture to an edge/periphery of the substrate 402surface. It is noted that the edge/periphery region of the substrate 402as described herein may refer to a substrate 402 edge region betweenabout 1 mm and about 5 mm from the substrate edge/bevel for a 300 mmsubstrate or between about 145 mm and about 149 mm from the substratecenter point/center line (e.g. a diameter passing through the substratecenter point). It should also be understood that gas flows during eitherthe plasma treatment process or annealing process of block 530 may alsoserve to purge the process chamber.

In one implementation, the purge gas mixture supplied in the metaldeposition process may include at least a hydrogen containing gas and aninert gas. It is noted that the purge gas mixture may be supplied withthe deposition precursor gas mixture during the deposition process asneeded. Suitable examples of the hydrogen containing gas may include H₂,H₂O, H₂O₂ or the like. Suitable examples of the inert gas include Ar,He, or Kr. In one particular implementation, the purge gas mixturesupplied during the metal deposition process may include H₂ and Ar gas.

In one implementation of the deposition process, a pulse of thedeposition precursor gas mixture along with a reducing gas andoptionally a purge/carrier gas mixture is supplied to the processingchamber 150. The term pulse as used herein refers to a dose of materialinjected into the process chamber. The pulse of the deposition precursorgas mixture continues for a predetermined time interval. Between eachpulse of the deposition precursor gas mixture and the plasma treatmentprocess, the purge gas mixture may be pulsed into the processing chamberin between each or multiple pulses of the deposition precursor gasmixture to remove the impurities or residual precursor gas mixture whichis unreacted/non-absorbed by the substrate 402 surface (e.g., unreactedcarbon containing impurities from the cobalt precursor or others) sothey may be pumped out of the processing chamber.

The time interval for the pulse of the deposition precursor gas mixtureis variable depending on a number of factors such as, film thicknessrequirement, process chamber volume, throughput concern, gas flow rate,and the like. In one implementation, the process conditions areadvantageously selected so that a pulse of the deposition precursor gasmixture provides a sufficient amount of precursor, such that at least amonolayer of the cobalt metal precursor is adsorbed on the substrate402. Thereafter, excess cobalt metal precursor remaining in the chambermay be removed from the processing chamber and pumped out by the purgegas mixture.

In some implementations, the reducing gas mixture may be suppliedconcurrently with the deposition precursor gas mixture in a single pulseto form the metal layer 420. In one implementation depicted herein, thepulse of the reducing gases may be co-flowed with the depositionprecursor gas mixture after a first few pulses, such as between first tofifth pulses, of the deposition precursor gas mixture.

In operation at block 510, a first pulse of the deposition precursor gasmixture is pulsed into the processing chamber 150 to deposit a portionof the metal layer 420 on the substrate. Each pulse of the depositionprecursor gas mixture into the processing chamber 150 may deposit ametal layer (e.g., a cobalt layer) having a thickness between about 5 Åand about 100 Å. During pulsing of the deposition precursor gas mixture,several process parameters are also regulated. In one implementation,the process pressure is controlled at between about 7 Torr and about 30Torr. The processing temperature is between about 125 degrees Celsiusand about 250 degrees Celsius. For plasma enhanced processes, the RFpower may be controlled at between about 100 Watts and about 1200 Watts.The cobalt gas precursor supplied in the deposition precursor gasmixture may be controlled at between about 1 sccm and about 10 sccm. Thereducing gas, such as the H₂ gas, may be supplied at between about 100sccm and about 10,000 sccm, such as between about 3000 sccm to about5000 sccm. The H₂ gas supplied from the substrate edge/substrate bottommay be controlled at between about 200 sccm and about 1000 sccm. Argongas may be supplied from the substrate edge/substrate bottom at betweenabout 200 sccm and about 1000 sccm.

Optionally, after block 510, the process chamber may be purged. Afterpulsing of the deposition precursor gas mixture, a purge gas mixture isthen supplied into the processing chamber to purge out the residuals andimpurities from the processing chamber. During pulsing of the purge gasmixture, the process pressure may be pumped down to a certain low level,such as lower than 2 Torr, for example lower than 0.5 Torr, at arelatively short time interval, such as between about 1 second and about5 seconds, so as to assist rapidly pumping out the residuals andimpurities from the processing chamber. Several process parameters arealso regulated during pulsing of the purge gas mixture. In oneimplementation, the process pressure is controlled at between about 0.1Torr and about 2 Torr, such as 0.1 Torr and about 1 Torr, for examplebetween about 0.1 Torr and about 0.6 Torr. The processing temperature isbetween about 125 degrees Celsius and about 250 degrees Celsius. The RFpower may be controlled at between about 100 Watts and about 800 Watts.The H₂ gas supplied in the purge gas mixture may be controlled atbetween about 200 sccm and about 1000 sccm. The Ar gas may be suppliedat between about 200 sccm and about 1000 sccm.

At block 530, subsequent to either exposing the substrate 402 to adeposition gas at block 510 or purging the deposition chamber at block520 the substrate 402 is exposed to either a plasma treatment process oran annealing process. The plasma treatment process or annealing processreduces surface roughness and improves the resistivity of the asdeposited portion of the metal layer 420.

Exemplary plasma forming gases for the plasma treatment process of block530 include hydrogen (H₂), nitrogen (N₂), ammonia (NH₃), andcombinations thereof. During the plasma treatment process, severalprocess parameters are also regulated. In one implementation, theprocess pressure is controlled at between about 7 Torr and about 30Torr. The processing temperature is between about 125 degrees Celsiusand about 250 degrees Celsius. The RF power may be controlled at betweenabout 100 Watts and about 800 Watts, for example, about 400 Watts. Theplasma forming gas, such as H₂ gas, may be supplied at between about3000 sccm and about 5000 sccm, for example, about 4000 sccm. The H₂ gassupplied from the substrate edge/substrate bottom may be controlled atbetween about 200 sccm and about 1000 sccm. The Ar gas may be suppliedfrom the substrate edge/substrate bottom at between about 200 sccm andabout 1000 sccm.

It has been shown that the plasma treatment either during deposition orafter deposition helps reduce the surface roughness of the as-depositedfilm and helps reduce carbon impurities in the as-deposited film. Thus,H radical life time, especially inside the narrow (<15 nm criticaldimension and >5 aspect ratio) via and trench structures expected fortransistor technology node ≤14 nm, is an important parameter to enableseamless and void-free cobalt gap fill. The lifetime of the H radicalinside the chamber during a CVD process can be improved by flowing aninert gas, such as He, Ne, Ar, among others, during the plasma treatmentusing an inductively coupled plasma source, microwave plasma source, ore-beam plasma source. The plasma sources are available from AppliedMaterials, Inc. or other vendors.

In some implementations, the annealing process of block 530 is ahydrogen purge process. In some implementations, the annealing processof block 530 may have a temperature range between about 50 degreesCelsius and about 1400 degrees Celsius (e.g., between about 50 degreesCelsius and 500 degrees Celsius; between about 100 degrees Celsius andabout 300 degrees Celsius; between about 300 degrees Celsius and 500degrees Celsius). During the thermal annealing process, a gas mixtureincluding at least a hydrogen containing gas and/or an inert gas (e.g.,argon) is supplied into the chamber. The gas mixture may be supplied tothe annealing chamber using either a static process where the chamber isfilled with gas prior to the anneal process or a continuous flow processwhere the gas mixture is continuously flowed through the chamber duringthe anneal process.

In one implementation, where the annealing process at block 530 is ahydrogen purge process, the hydrogen purge process may be performed bysupplying a gas mixture including at least one of a hydrogen containinggas, an inert gas, and a nitrogen containing as into the annealingchamber at a flow rate between about 1,000 sccm and about 30,000 sccm,for example, between about 5,000 sccm and 15,000 sccm, controlling achamber pressure of about 5 Torr to about 1,000 Torr (e.g., betweenabout 5 Torr and about 60 Torr; between about 20 Torr and about 40Torr), maintaining a temperature range between about 50 degrees Celsiusand about 500 degrees Celsius (e.g., between about 100 degrees Celsiusand about 300 degrees Celsius; between about 300 degrees Celsius and 500degrees Celsius), for example, between about 100 degrees Celsius andabout 300 degrees Celsius. The thermal annealing process of block 530may be performed, optionally while rotating the substrate, for betweenabout 30 seconds and about 600 seconds. Suitable examples of gases forthe gas mixture supplied in the chamber may include at least one of ahydrogen gas, a nitrogen containing gas, an inert gas (e.g., argon) orother gases as needed. In some implementations, where the annealingprocess of block 530 includes the hydrogen purge process, thetemperature for the process of block 530 may be the same as or similarto the temperature used to deposit the metal layer in block 510.

In some implementations, the thermal annealing process may be performedin-situ in the same processing chamber as the cyclic metal depositionprocess. In some implementations where both the metal layer depositionand anneal may be performed in the same chamber if the chamber has thecapability to heat the substrate to temperatures required forprocessing. In some implementations, the thermal annealing process maybe performed in a separate processing chamber.

It has been shown that carbon impurities can be reduced by the hydrogenpurge/anneal as demonstrated by resistivity reduction.

Subsequent to exposing the substrate to either a plasma treatmentprocess or an annealing process in block 530, the deposition chamber mayoptionally be purged in block 540. The optional purge of block 540 maybe performed similarly to the purge process described in block 520.

At block 550, if the predetermined thickness of the metal layer 420 hasnot been achieved, additional cycles starting from exposing thesubstrate to the deposition precursor gas mixture followed with theplasma pretreatment process can then be repeatedly performed until adesired thickness range of the metal layer 420 is reached. If thepredetermined thickness of the metal layer has been achieved, theprocess proceeds to block 350 where a thermal annealing process isperformed.

For example, if the total thickness of the metal layer is 10 nm and theportion of the metal layer is deposited at 2 nm/cycle then 5 cycles of(2 nm deposition followed by plasma treatment) will be needed.

At block 350, a thermal annealing process is performed in a chamber onthe substrate 402 to improve the properties of the metal layer 420. Insome implementations, the thermal annealing process may be performedin-situ in the same processing chamber as the cyclic metal depositionprocess. In some implementations, the thermal annealing process may beperformed in a separate processing chamber. The thermal annealingchamber may be one of the processing chambers 212, 214, 216, 232, 234,236, 238 of the system 200 as needed. In one implementation, the thermalannealing process performed at block 350 may have a temperature rangebetween about 200 degrees Celsius and about 1400 degrees Celsius (e.g.,between about 200 degrees Celsius and about 500 degrees Celsius; betweenabout 300 degrees Celsius and about 500 degrees Celsius). During thethermal annealing process, a gas mixture including at least a hydrogencontaining gas and/or an inert gas (e.g., argon) is supplied into theannealing chamber. The gas mixture may be supplied to the annealingchamber using either a static process where the chamber is filled withgas prior to the anneal process or a continuous flow process where thegas mixture is continuously flowed through the annealing chamber duringthe anneal process.

In one implementation, the thermal annealing process at 350 may beperformed by supplying a gas mixture including at least one of ahydrogen containing gas, an inert gas, and a nitrogen containing as intothe annealing chamber at a flow rate between about 100 sccm and about2000 sccm, controlling a chamber pressure of about 0.5 Torr and about 15Torr, for example, between about 5 Torr and about 8 Torr, maintaining atemperature range between about 150 degrees Celsius and about 500degrees Celsius, for example, between about 300 degrees Celsius andabout 475 degrees Celsius, and performing the thermal annealing process,optionally while rotating the substrate, for between about 30 secondsand about 600 seconds. Suitable examples of gases for the gas mixturesupplied in the thermal annealing chamber may include a hydrogen gas, anitrogen containing gas, an inert gas (e.g., argon) or other gases asneeded. In one implementation, the gas mixture supplied into theprocessing chamber to perform the silicidation process includes hydrogengas (H₂) supplied at a flow ratio between about 1:10 and about 1:1, suchas about 1:3.

An example of a suitable thermal processing chamber, in which block 350may be performed, is a dual mode degas (DMD) chamber, available fromApplied Materials, Inc. Other examples of suitable thermal processingchambers are the Vantage® Vulcan™ RTP chamber and the Vantage® Astra™DSA chamber or batch furnace tool. It should be noted that the annealingprocess may not necessarily be integrated with the metal layer 420deposition chamber. The use of RTP and DSA anneal may provide forfurther control of temperature uniformity and rapid temperature change.It is noted that other thermal annealing chamber available from othermanufactures may also be utilized to practice the present disclosure.

After the thermal annealing process is completed, at block 360, if thepredetermined thickness of the metal layer 420 has not been achieved,additional cycles starting from performing a cyclic metal deposition todeposit a metal layer at block 340 followed by performing an annealingprocess on the metal layer at block 350 can then be repeatedly performeduntil a desired thickness range of the metal layer 420 is reached. Ifthe predetermined thickness of the metal layer has been achieved, theprocess is complete and additional processing steps may be performed.

Thus, according to the aforementioned implementations, methods fordepositing a metal layer in a feature definition are provided. Themethods include filling feature definitions with seamless metal layersby annealing the as-deposited metal layers. Annealing of CVD cobaltfilms results in a bottom-up, seamless gap fill. In certainimplementations, a wetting layer is not required for reflow of cobalt.Thickness of the metal layer (e.g., CVD cobalt layer) may be less than50% of the feature definition diameter (critical dimension). A cyclicprocess utilizing a combination of thin cobalt film deposition andshort-time anneal is used. Ambience during the short-time anneal lowersthe required anneal temperature to achieve seamless cobalt fill. Ablanket wafer study demonstrates 50% reduction in resistivity of cobaltfilms after the anneal treatment. Variations of anneal time,temperature, atmosphere (type of gas used), static gas pressure or gasflow during the anneal step may be used to reduce roughness and improvethe resistivity of the metal layer. Short anneal time (e.g., 1 minute)is sufficient to reduce cobalt resistivity and roughness. Gas flowduring anneal further improves the resistivity of cobalt films. Argonand hydrogen gas or a combination of both may be used for annealatmosphere. PVD cobalt can be utilized in place of CVD cobalt. Acombination of CVD and PVD can also be utilized where CVD cobalt acts asa wetting layer for PVD cobalt re-flow.

FIG. 6 depicts a flow diagram for forming a metal layer in a featuredefinition of a semiconductor device in accordance with oneimplementation of the present disclosure. The sequence described in FIG.6 corresponds to the fabrication stages depicted in FIGS. 7A-7E, whichare discussed below. FIGS. 7A-7E illustrate schematic cross-sectionalviews of a substrate 402 having a device structure 408 formed thereonduring different stages of fabricating a metal layer 420 within featuredefinitions 406 a, 406 b of the device structure 408 illustrated by theprocessing sequence 600. The sequence of FIG. 6 is generally providedwith reference to a CVD, ALD, or PVD deposited cobalt metal layer.

Certain aspects of the processing sequence 600 are similar to processingsequence 300 described with reference to FIG. 3 and will not be repeatedhereinafter for the sake of brevity. In one implementation, blocks 610and 620 are similar to blocks 310 and 320 depicted in FIG. 3 asdescribed above. Blocks 610 and 620 correspond to the fabrication stagesdepicted in FIGS. 7A and 7B, respectively. A detailed discussion ofFIGS. 7A and 7B may be found with reference to FIGS. 4A and 4B. However,performing a pretreatment process on the substrate may be optional inblock 620.

Block 630 provides for performing a barrier layer deposition to deposita barrier layer 416 on the substrate 402, as shown in FIG. 7C. Thebarrier layer generally contains a metal or a metal nitride material,such as titanium (Ti), titanium nitride (TiN), alloys thereof, orcombinations thereof. The barrier layer 416 may also comprise plasmanitrided (N₂ or NH₃) Ti and PVD Cobalt. If the barrier layer 416comprises a nitrided Ti layer, only the top few angstroms of titaniumare converted to a TiN compound. It has been found that non-oxidized Tiand TiN barrier layers provide for improved diffusion resistance. Thebarrier layer 416 may have a thickness within a range from about 2 Å toabout 100 Å, more narrowly within a range from about 3 Å to about 80 Å,more narrowly within a range from about 4 Å to about 50 Å, more narrowlywithin a range from about 5 Å to about 25 Å, more narrowly within arange from about 5 Å to about 20 Å, more narrowly within a range fromabout 5 Å to about 15 Å, and more narrowly within a range from about 5 Åto about 10 Å. The barrier layer is generally deposited by atomic layerdeposition (ALD), plasma-enhanced ALD (PE-ALD), chemical vapordeposition (CVD), or physical vapor deposition (PVD) processes.

In one implementation, performing a barrier layer deposition comprisesan ALD process comprising providing a Ti containing precursor, which maybe provided to the chamber in the presence of a carrier gas, such as aninert gas. In another implementation, a Ti containing precursor may beprovided with a nitrogen containing precursor to form a barrier layercomprising TiN. The Ti containing precursor and the nitrogen containingprecursor may be provided in the presence of a carrier gas, such as aninert gas. In another implementation, a nitridation process may beperformed on a deposited Ti layer to form a TiN barrier layer. Inanother implementation, the Ti barrier layer is deposited by a PVD Tiprocess.

Block 635 provides for performing a wetting layer deposition to deposita wetting layer 718 on the substrate 402, as shown in FIG. 7D. Thewetting layer 718 is deposited over the barrier layer 416. The wettinglayer is generally deposited by a process selected from PVD Co, CVD TiN,PVD TiN, CVD Ru, PVD Ru, nitridation of PVD Ti, or combinations thereof.In implementations using a CVD process to deposit the wetting layer 718,a desired precursor gas is provided to the chamber and may be furtherprovided in the presence of a carrier gas. In implementations using aPVD process to deposit the wetting layer 718, a target comprising thedesirable material to be deposited is provided and a PVD process isperformed to deposit a PVD wetting layer. In one implementation, thewetting layer comprises PVD TiN. In this implementation, a Ti target isprovided and bombarded with ions to sputter Ti to deposit the wettinglayer 718 over the barrier layer 416. A nitridation process using anitrogen containing precursor, such as NH₃, in the presence of a plasmais performed on the PVD Ti layer to form the TiN wetting layer 718. Inthis implementation, the wetting layer 718 comprises a nitrided Ti layerand only the top few angstroms of titanium are converted to a TiNcompound. In another implementation, the wetting layer is PVD Co. Inthis implementation, a Co target is provided and bombarded with ions tosputter cobalt to deposit the wetting layer 718 over the barrier layer416. In the implementation using PVD Co, RF power is provided at afrequency from about 5000 W to about 6000 W, such as about 5500 W. Apower of the PVD Co process is provided from about 400 W to about 600 W,such as about 500 W and the pressure of the chamber while performing thePVD Co process is from about 50 mT to about 150 mT, such as about 100mT.

It should be known that a wetting layer of Ti or TiN may be deposited inthe same chamber (under high vacuum) as a subsequent CVD Co depositionprocess. In an alternate implementation, agglomeration of CVD Co filmsduring anneal involved using CVD Co (with different film properties) asa wetting layer. This CVD Co wetting layer included high carbon atomic%>5% carbon compared to <1% carbon for CVD Co films used for gap-fillpurpose. The high carbon content CVD Co films were obtained using lowerH₂ partial pressure during deposition step and by eliminating cyclic H₂plasma treatment.

It should be noted that any of the aforementioned wetting layer 718processes may be performed with the subsequent metal layer depositionprocess, which is provided at block 640. The wetting layer 718 and thebarrier layer 416 generally enhance the subsequent metal layerdeposition. It has been found that voids may form at the bottom of afeature definition on the substrate or at other locations in the featuredefinition. The voids are believed to be formed as a result ofagglomeration, or the accumulation of the metal layer, when the metallayer is annealed. The voids are generally undesirable because a voidbetween the substrate and the metal layer ultimately reduces the qualityof the metal layer and negatively affects overall device performance.Further, inter-diffusion between the metal layer and the underlyingsubstrate during anneal processes result in Co and siliconinter-diffusion. The inter-diffusion negatively affects deviceperformance and leads to unpredictable device behavior. The barrierlayer 416, either alone or in combination with the wetting layer 718,reduces the Co and silicon inter-diffusion. Further, the wetting layer,either alone or in combination with the barrier layer 416, enhances theadhesion of the metal layer when it is deposited to fill the vias andtrenches of the device by reducing the probability of agglomerationduring subsequent anneal processes.

In an alternate implementation, agglomeration of CVD Co films during ananneal process may use CVD Co as a wetting layer. This CVD Co wettinglayer may include a high carbon content (atomic %>5%) as compared to alow carbon content (atomic %<1%) carbon for CVD Co films used forseamless gap-fill. The high carbon content CVD Co films were obtainedusing lower H₂ partial pressure during the deposition step and byeliminating cyclic H₂ plasma treatment.

Block 640 provides performing a cyclic metal deposition to deposit ametal layer on the substrate. The process parameters and description ofthe cyclic metal deposition process may be found above with regard toblock 340 in FIG. 3 and the corresponding description related to FIG. 5.Block 650 provides for performing an annealing process on the metallayer disposed on the substrate. The process parameters and descriptionof the performing an annealing process may be had with reference toblock 350 in FIG. 3.

After the thermal annealing process is completed, at block 660, if thepredetermined thickness of the metal layer 420 has not been achieved,additional cycles starting from performing a cyclic metal deposition todeposit a metal layer at block 640 followed by performing an annealingprocess on the metal layer at block 650 can then be repeatedly performeduntil a desired thickness range of the metal layer 420 is reached. Ifthe predetermined thickness of the metal layer has been achieved, theprocess is complete and additional processing steps may be performed.

As noted above, the processing sequence 600 described in FIG. 6, may behad with reference to CVD, ALD, or PVD metal deposition processes. Anintegrated (non-oxidized) CVD or ALD TiN barrier layer reduced thepresence of voids at the bottom of the device feature definition. Avacuum break may be introduced after the wetting layer 718 deposition orafter the metal layer 420 deposition before performing the annealprocess of block 650. It should be noted that the anneal process ofblock 650 may be performed in a chamber other than the chamber in whichthe metal layer 420 was deposited. Moreover, it was found that a highfrequency of H₂ plasma treatment (plasma treatment at a CVD Co thicknessof 20 Å or less), as provided at block 640 (See FIG. 5 for relatedplasma processing parameters), played a significant role in eliminatingvoid formation at the bottom of the device feature definitions. Finally,it has been found that the reflow characteristics of CVD or ALD metallayers may be regulated by controlling the atomic percent of impurities(i.e. carbon, oxygen, nitrogen, etc.) by the aforementioned processvariables provided in the processing sequence 600. A one percent orlower carbon impurity level may be preferable for enabling a seamlessmetal layer gap-fill, more specifically, a seamless cobalt gap-fill. Inaddition to the process variables of the metal layer deposition, theimpurity levels may be further controlled by the barrier layer 416 andthe wetting layer 718.

FIG. 8 depicts a flow diagram for forming a metal layer in a featuredefinition of a semiconductor device in accordance with oneimplementation of the present disclosure. The sequence described in FIG.8 corresponds to the fabrication stages depicted in FIGS. 7A-7E, whichare discussed below. FIGS. 7A-7E illustrate schematic cross-sectionalviews of a substrate 402 having a device structure 408 formed thereonduring different stages of fabricating a metal layer 420 within featuredefinitions 406 a, 406 b of the device structure 408 illustrated by theprocessing sequence 800. The sequence of FIG. 8 is generally providedwith reference to a PVD deposited cobalt metal layer.

Processing sequence 800 begins by providing a substrate at block 810. Adetailed description of block 810 may be had by reference to thedescriptions related to blocks 310 in FIG. 3 and block 610 in FIG. 6.Block 820 provides for optionally performing a pretreatment process onthe substrate. A detailed description related to block 820 may be had byreference to the descriptions related to block 320 in FIG. 3 and block620 in FIG. 6.

Block 830 provides performing a barrier layer deposition to deposit abarrier layer in the feature definition. A general description regardingthe barrier layer 416 may be had with reference to block 630 in FIG. 6.In one implementation, the barrier layer 416, such as a TiN barrierlayer, is disposed on the substrate. In this implementation, the TiNlayer is provided at a thickness of between about 5 Å and about 75 Å,such as about 50 Å. However, it has been shown that a 10 Å TiN layer maybe sufficient as a barrier layer. The TiN barrier layer is formed by NH₃or N₂ nitridation of a previously deposited Ti layer or by a CVDdeposition process. Processing parameters for the deposition of the TiNbarrier layer may be found with regard to block 630 in FIG. 6.

Block 835 provides performing a wetting layer deposition to deposit awetting layer on the barrier layer. A general description of the wettinglayer 718 may be had with reference to block 635 in FIG. 6. In oneimplementation, the wetting layer 718 is deposited by a CVD or ALDprocess. Suitable processes for providing the wetting layer 718 includeCVD TiN, CVD Co, CVD Ru, ALD TaN, and combinations thereof. In oneimplementation, the wetting layer may be deposited by a CVD Co process.The cobalt deposited during the CVD process is provided to theprocessing chamber by a cobalt containing precursor, such as the cobaltcontaining precursors discussed with reference to the cyclic metaldeposition process provided in FIG. 3. In one implementation, the cobaltcontaining precursor is provided to the chamber in a thermal depositionprocess. The thermal deposition process generally comprises heating thesubstrate 402 to promote deposition of the cobalt on the surface of thesubstrate 402. In one implementation, the thermal deposition processprovides for heating the substrate from about 100° C. to about 200° C.,such as about 150° C. In this implementation, the cobalt depositedduring the CVD Co process is the wetting layer 718, which is disposedover the barrier layer 416.

Block 840 provides for performing an annealing process on the wettinglayer 718. The annealing process is generally performed to reduce thesurface roughness of the wetting layer 718, increase grain size of thecrystalline structure, and reduce impurities, such as carbon, that maybe present in the wetting layer 718. The annealing process is performedat a temperature of between about 200° C. to about 500° C., such asabout 400° C. The annealing process may be performed in a chamberenvironment where an inert gas, such as argon, is provided in thechamber. In one implementation, argon gas is static within the chamberand the chamber may be optionally purged after the annealing of thewetting layer 718 is performed. In one implementation, the annealingprocess is performed for a duration of between about 10 seconds to about1000 seconds, such as between about 30 seconds and about 90 seconds,such as about 60 seconds. In another implementation, the annealingprocess may be performed in a chamber environment where H₂ gas isprovided to the chamber in a static or flowing manner. In thisimplementation, the annealing process may be performed for a duration ofbetween about 10 seconds to about 1000 seconds. In otherimplementations, the annealing process may be performed with the argongas and H₂ gas.

Block 850 provides for performing a metal deposition process fordepositing a metal layer 420 on a substrate. In one implementation, themetal layer 420 is deposited by a PVD Co process. The PVD Co process mayfurther be a thermal PVD Co process. The cobalt is sputtered usingconventional processes, and in one implementation, the sputteringprocess is performed in the presence of a process gas, such as argon orH₂. In one implementation, the PVD Co process may be performed byproviding RF power at a frequency from about 5000 W to about 6000 W,such as about 5500 W. The RF may be provided in a direct current at apower of between about 250 W and about 750 W, such as about 500 W. Thepressure of the chamber during the PVD Co process may be maintained at apressure of between about 50 mTorr and about 200 mTorr, such as about100 mTorr. Once the cobalt has been sputtered to the substrate, thecobalt may be reflowed by providing heat to the substrate to reflow theas deposited cobalt. In one implementation, the PVD Co reflow may beperformed by heating the substrate to a temperature of between about200° C. to about 500° C. In implementations where a PVD Co process isemployed, both the metal layer 420 deposition and anneal may beperformed in the same chamber if the chamber has the capability to heatthe substrate to temperatures required for processing.

Block 860 provides for exposing the metal layer 420 to either a plasmatreatment process or an annealing process. The plasma treatment processgenerally comprises providing a process gas, such as H₂, to the chamberand applying an RF current to form the process gas into a plasma. In oneimplementation, the frequency of the RF current is provided betweenabout 200 W and about 800 W, such as about 400 W. The plasma treatmentprocess is performed for about 1 second to about 60 seconds, such asabout 30 seconds. In one implementation, the substrate 402 may be heatedto a temperature of between about 100° C. to about 200° C., such asabout 150° C. to further reduce the surface roughness of the metal layer420 and reduce the percentage of impurities that may be present in themetal layer 420.

The annealing process of block 860 may be the same as or similar to thehydrogen purge annealing process described in block 530.

Block 870 provides for performing an annealing process on the metallayer 420 disposed in the feature definitions 406 a, 406 b. Theannealing process is generally performed to reduce the surface roughnessof the metal layer 420 and reduce impurities, such as carbon, that maybe present in the metal layer 420. Further, the annealing processincreases crystalline grain size, which results in lower resistivity,resulting in improved integrated circuit performance. The annealingprocess is performed at a temperature of between about 200° C. to about500° C., such as about 400° C. The annealing process is furtherperformed in a chamber environment where an inert gas, such as argon,and a process gas, such as H₂, are provided in the chamber. In oneimplementation, argon and H₂ gas are flowing within the chamber and thechamber may be optionally purged after the annealing of the metal layer420 is performed. In one implementation, the annealing process isperformed between about 30 seconds and about 90 seconds, such as about60 seconds.

In the implementations above, the PVD Co process may be performedwithout a cyclic metal deposition process if the Co deposition andanneal process are performed in a chamber that provides for heating thesubstrate. In an alternative implementation, a PVD Co layer may bedeposited at the bottom of a feature definition and may be etched andre-sputtered on the feature definition sidewall to provide a continuouscobalt film on the sidewall, which allows for reflow of the PVD Co fromthe field to the bottom of the feature definition. The metal layer 420deposition is performed to obtain a sufficient film thickness requiredfor a subsequent chemical mechanical polish of the metal layer 420.

In another implementation, the wetting layer 718 comprises CVD Co andthe metal layer 420 comprises tungsten (W). This implementation isgenerally used with a dual damascene type structure having a lower partof the feature definition exhibiting a small critical dimension andaggressive aspect ratio. The upper portion of the dual damascene typestructure generally has a greater critical dimension and less aggressiveaspect ratio when compared to the lower portion. In this implementation,the lower portion, which presents additional metal layer depositionchallenges, may be filled with a CVD Co process as described above. TheCVD Co process fills the lower portion of the feature definition.Following the CVD Co deposition, a CVD W process may be performed tofill the remaining portion of the feature definition. The CVD W processgenerally deposits material at a faster rate than the CVD Co process,thus allowing for increased throughput.

FIG. 9 depicts a cross-sectional view of a substrate containing metallayers used as a conformal gate electrode 950 and deposited according tocertain implementations described herein, which may be used in a Logicapplication. Additionally, the semi-conductor structure of FIG. 9 may beused in planar and three dimensional transistors having gate structures.Examples of three dimensional transistors having gate structures includea FinFET (a nonplanar, double-gate transistor built on silicon oninsulator technology substrate, based on the earlier DELTA (single-gate)transistor design) or a Trigate transistor structure.

In one implementation, the metal layer described herein may be used in ametal gate structure. For example, FIG. 9 depicts a semiconductorstructure, which may be used in a Logic application, having ametal-containing gate electrode 950 containing a metal layer depositedby methods described herein. An initial feature definition 955 is formedin a high-k dielectric material 960 that was previously deposited on thesubstrate.

A work function material layer 970 is then conformally deposited in thefeature definition formed in the high-k dielectric material 960. Themetal gate fill material 980 is then formed on the work functionmaterial layer 970 and fills the feature definition 955.

A metal gate fill material is used to complete the gate electrode 950 asshown in FIG. 9. The work function material layer 970 and the metal gatefill material 980 may be the same or different material depending on therespective conductivity desired for the gate electrode 950. If a metalgate fill material is used that is different than the work functionmaterial, the metal gate fill material may include an electricallyconductive material, such as a metal or a metal alloy. Examples of ametal or a metal alloy for use as a metal gate fill material includematerials from the group of tungsten, aluminum, copper, cobalt, andcombinations thereof, and alloys of tungsten, aluminum, copper, cobaltand combinations thereof.

If the metal gate fill material is used that is the same orsubstantially the same as the work function material, the metal gatefill material 980 may comprise the metal layers described herein and bedeposited by the processes described herein. Alternatively, the workfunction material layer 970 and the metal gate fill material 980 may bedifferent materials that are both selected from the metal layersdescribed herein, metal carbide, metal carbide silicide, or metalcarbide nitride materials. For example, the high-k dielectric constantmaterial may be hafnium oxide, the work function material layer 970 maybe hafnium carbide, and the gate fill material may be tantalum carbide.The gate fill material should have an equal or lesser resistivity thanthe work function material layer.

Optionally, a wetting layer may be deposited prior to the deposition ofthe metal gate fill material 980. The wetting layer may be a metalmaterial selected from the group of cobalt, tantalum, titanium, andcombinations thereof. Alternatively, a barrier layer, which may also beused in conjunction as a wetting layer or perform as a wetting layer,may be deposited before or after the work function material layer. Thebarrier layer may comprise any suitable barrier layer for the fillmaterial, i.e., tungsten, copper, and aluminum, and may be ametal-containing material selected from the group of tantalum nitride,titanium nitride, tungsten nitride, and combinations thereof. A barrierlayer deposited before the work function material layer 970 is shown inlayer 965 by broken lines. A barrier layer and/or a wetting layerdeposited after the work function material layer 970 but before themetal gate fill material 980 is shown in layer 975 by broken lines. Eachof the barrier and/or wetting layers may be deposited to a thickness of50 Å or less, such as from about 1 Å to about 20 Å.

FIG. 10 depicts a cross-sectional view of a CMOS structure 1000 havingNMOS and PMOS aspects formed according to certain implementationsdescribed herein. The CMOS structure 1000 may comprise a substrate 1002having an epitaxial layer 1004 deposited thereover. Within the epitaxiallayer 1004, a p-well 1006 and an n-well 1008 may be formed. Over thep-well 1006, an NMOS structure 1018 may be formed. The NMOS structure1018 may comprise a source electrode 1010 a, a drain electrode 1010 b, ahigh-k dielectric layer 1012, a capping layer 1014, and a gate electrode1016. Similarly, a PMOS structure 1028 may be formed over the n-well1008. The PMOS structure 1028 may comprise a source electrode 1020 a, adrain electrode 1020 b, a high-k dielectric layer 1022, a capping layer1024 and a gate electrode 1026. The NMOS structure 1018 may be isolatedfrom the PMOS structure 1028 by an isolation region 1030.

The capping layers 1014, 1024 may be present between the high-kdielectric layers 1012, 1022 and the gate electrodes 1016, 1026 toprevent the gate electrodes 1016, 1026 from reacting with the high-kdielectric layers 1012, 1022. The capping layers 1014, 1024 may tune thethreshold voltage. In one implementation, the capping layer 1014 in theNMOS structure 1018 is different than the capping layer 1024 of the PMOSstructure 1028. For the NMOS structure 1018, the high-k dielectric layer1012 may be hafnium oxide, and the gate electrode 1016 may comprise ametal deposited according to the implementations described herein.

While the foregoing is directed to implementations of the presentdisclosure, other and further implementations of the disclosure may bedevised without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

The invention claimed is:
 1. A method for depositing a cobalt metallayer for forming a semiconductor device, comprising: performing abarrier layer deposition process to deposit a barrier layer in a featuredefinition formed in a substrate, wherein the barrier layer depositionprocess comprises depositing a titanium barrier layer, a titaniumnitride barrier layer, or a titanium barrier layer followed by atitanium nitride barrier layer; performing a wetting layer depositionprocess to deposit a wetting layer on the barrier layer, wherein thewetting layer deposition process comprises depositing a first cobaltlayer via a physical vapor deposition process; performing a cyclic metaldeposition process to deposit a second cobalt metal layer in the featuredefinition, comprising: exposing the substrate to a deposition precursorgas mixture to deposit a portion of the second cobalt metal layer in thefeature definition via a chemical vapor deposition process; exposing theportion of the second cobalt metal layer to either a plasma treatmentprocess or a hydrogen treatment process; repeating exposing thesubstrate to the deposition precursor gas mixture and exposing theportion of the second cobalt metal layer to either the plasma treatmentprocess or the hydrogen thermal treatment process until a predeterminedthickness of the second cobalt metal layer is achieved; and filling thefeature definition with the second cobalt metal layer.
 2. The method ofclaim 1, wherein the substrate includes at least a high-k dielectriclayer having the feature definition formed therein, wherein the secondcobalt metal layer is filled in the feature definition formed in thehigh-k dielectric layer.
 3. The method of claim 1, wherein the hydrogenthermal treatment process comprises supplying a gas mixture including atleast one of an inert gas and hydrogen gas (H₂) while providing heatenergy to the second cobalt metal layer at a temperature from about 100degrees Celsius to about 300 degrees Celsius.
 4. The method of claim 3,wherein exposing the substrate to the deposition precursor gas mixtureto deposit the portion of the second cobalt metal layer in the featuredefinition and exposing the portion of the second cobalt metal layer toeither the plasma treatment process or the hydrogen thermal treatmentprocess are performed in-situ in the same processing chamber.
 5. Themethod of claim 1, wherein exposing the substrate to the depositionprecursor gas mixture to deposit the portion of the second cobalt metallayer in the feature definition and exposing the portion of the secondcobalt metal layer to either the plasma treatment process or thehydrogen thermal treatment process are performed simultaneously.
 6. Themethod of claim 1, wherein exposing the portion of the second cobaltmetal layer to the plasma treatment process comprises supplying a gasselected from hydrogen (H₂), nitrogen (N₂), ammonia (NH₃), andcombinations thereof to reduce roughness of the portion of the secondcobalt metal layer.
 7. The method of claim 1, wherein the featuredefinition is selected from vias, trenches, lines and contact holes. 8.The method of claim 1, wherein the deposition precursor gas mixtureincludes a cobalt-containing precursor and a reducing gas.
 9. The methodof claim 1, wherein filling the feature definition with cobalt metalcomprises a PVD cobalt re-flow process.
 10. The method of claim 1,wherein the titanium barrier layer is deposited via a physical vapordeposition process and the titanium nitride barrier layer is depositedvia an atomic layer deposition process.
 11. The method of claim 1,further comprising thermally treating the wetting layer at a temperaturefrom about 200 degrees Celsius to about 500 degrees Celsius in anenvironment containing an inert gas, hydrogen gas, or a combinationthereof.
 12. A method for depositing a metal layer for forming asemiconductor device, comprising: performing a barrier layer depositionprocess to deposit a barrier layer in a feature definition formed in asubstrate, wherein the barrier layer deposition process comprisesdepositing a titanium barrier layer, a titanium nitride barrier layer,or a titanium barrier layer followed by a titanium nitride barrierlayer; performing a wetting layer deposition process to deposit awetting layer on the barrier layer, wherein the wetting layer depositionprocess comprises depositing a first cobalt layer via a physical vapordeposition process; performing a cyclic metal deposition process todeposit a second cobalt metal layer in the feature definition,comprising: exposing the substrate to a deposition precursor gas mixtureto deposit a portion of the second cobalt metal layer in the featuredefinition via a chemical vapor deposition process; exposing the portionof the second cobalt metal layer to a hydrogen thermal treatmentprocess; repeating exposing the substrate to the deposition precursorgas mixture and exposing the portion of the second cobalt metal layer tothe hydrogen thermal treatment process until a predetermined thicknessof the second cobalt metal layer is achieved; and filling the featuredefinition with the second cobalt metal layer.
 13. The method of claim12, wherein the substrate includes at least a high-k dielectric layerhaving the feature definition formed therein, wherein the second cobaltmetal layer is filled in the feature definition formed in the high-kdielectric layer.
 14. The method of claim 12, wherein the hydrogenthermal treatment process comprises supplying a gas mixture including atleast one of an inert gas and hydrogen gas (H₂) while providing heatenergy to the portion of the second cobalt metal layer at a temperaturefrom about 100 degrees Celsius to about 300 degrees Celsius.
 15. Themethod of claim 14, wherein exposing the substrate to the depositionprecursor gas mixture to deposit the portion of the second cobalt metallayer in the feature definition and exposing the portion of the secondcobalt metal layer to the hydrogen thermal treatment process areperformed in-situ in the same processing chamber.
 16. The method ofclaim 12, wherein exposing the substrate to the deposition precursor gasmixture to deposit the portion of the second cobalt metal layer in thefeature definition and exposing the portion of the second cobalt metallayer to the hydrogen thermal treatment process are performedsimultaneously.
 17. The method of claim 12, wherein filling the featuredefinition with the second cobalt metal layer comprises a PVD cobaltre-flow process.
 18. The method of claim 12, wherein filling the featuredefinition with the second cobalt metal layer comprises annealing thethe second cobalt metal layer.
 19. The method of claim 12, whereinfilling the feature definition with the second cobalt metal layercomprises annealing the second cobalt metal layer.
 20. The method ofclaim 12, further comprising thermally treating the wetting layer at atemperature from about 200 degrees Celsius to about 500 degrees Celsiusin an environment containing an inert gas, hydrogen gas, or acombination thereof.